The present invention relates to an extracorporeal lithotripter. Such lithotripters are known in the art, and utilized an ellipsoidal reflector. An ellipsoid will be recognized as a solid of revolution with two focal points. The ellipsoidal reflector is truncated short of the second focal point. A rubber or the like diaphragm closes the open end of the ellipsoidal reflector. The reflector is filled with water with a saline content, and a spark gap is provided at the first focus point in the reflector. The reflector is positioned adjacent a body having a kidney stone or other concretion to be disintegrated. The diaphragm presses against the body, and the second focal point of the ellipsoidal reflector is brought into coincidence with the kidney stone or other concretion. High voltage pulses produce sparks across the spark gap. These, in turn, flash some of the water into steam, and may also cause some dissociation of the hydrogen and oxygen. The result is a series of shockwaves or pulses. These shockwaves are focused by the walls of the reflector and pass through the water in the reflector, through the diaphragm, which is pressed against the skin of the body, and through the tissues of the body to focus on the second focus point coincident with the kidney stone or other concretion. A series of such shocks, generally less than an hour for a treatment, result in reduction of the stone to small particles which pass from the body with the urine.
Such treatment is effected from exteriorly of the body, and it may require no hospitalization, or sometimes merely overnight hospitalization. Advantages of a lithotripter with an isocentric system have previously been recognized, for example see Puppo U.S. Pat. No. 5,230,329. In such an isocentric system the reflector, often referred to as the shockhead, and the aiming or localization device or devices, such as an X-ray system are supported for rotation about a common center. The concretion to be destroyed is positioned on this center, and the aiming system can be moved to locate the stone from different angles, and the shockhead can be moved to cause the shockwaves to attack the concretion from different angles, thereby hastening destruction thereof. In the system disclosed by Puppo in U.S. Pat. No. 5,230,329 the aiming or localization system, and the shockhead are mounted on a common ring. This has advantages in rigidity and balance. However, other advantages can be realized by separately mounting the shockhead and the localization system for independent rotation about a common center. Independent movement of the radiological localization or aiming apparatus and of the shockhead, both aimed at the isocenter of the system permits the doctor or clinician to choose the most convenient angle of approach to the patient by simple positioning of the shockhead. For example, the patient can be treated in supine, prone, or lateral positions with a choice of dorsal, ventral or lateral approach. The patient is not moved between localization and treatment, thus insuring high accuracy of the stone localization process. Localization is effective by means of fluoroscopic or X-ray techniques. This is done by making a biplane sighting of the calculus at two different angles, and centering the target in each. Initially, the radiological axis is placed in a vertical position and the table supporting the patient is moved horizontally in order the center the stone in the field of view. At this point, the stone lies on the vertical axis of the system. Subsequently, the fluoroscopy apparatus is moved to an arbitrary position, and a second sighting is made. The table then is moved only vertically to center the stone, bringing it into focus. It be emphasized that this is also the treatment position. The patient is not moved thereafter. This method of localization is rapid, and does not suffer from any loss of accuracy caused by excessive patient movement. The angle between the two radiological projections is not fixed, but can be suitably chosen by the physician to reflect clinical needs.